11-Azidoundecanoic acid, a click chemistry reagent with an azide group, serves as a hydrophobic bioconjugation linker amenable to further modification via Staudinger ligation or Click chemistry. This compound is recognized as a substrate by lipoic acid ligase (LpIA) for labeling purposes [1] [2]. Additionally, 11-Azidoundecanoic acid can participate in copper-catalyzed azide-alkyne cycloaddition (CuAAc) with alkyne-bearing molecules and engage in strain-promoted alkyne-azide cycloaddition (SPAAC) with molecules featuring DBCO or BCN groups.

The microbial lipoic acid ligase (LplA) specifically attaches an alkyl azide to an engineered LplA acceptor peptide (LAP), which then selectively reacts with cyclooctyne conjugates, linking various probes. This method facilitates broad application in biochemical and imaging analyses of cell surface proteins, employing small fluorophores coupled through a concise peptide tag.